1. Field of the Invention
The present invention relates to a semiconductor device using a lead frame including discrete leads and common leads, and more particularly to a semiconductor device including common leads of which outer portions have a coupling portion and which are bridged with brazing material (e.g., solder or the like) in order to enhance a heat dissipation effect.
2. Description of the Related Art
Recently, higher-density semiconductor devices have been sought in order to comply with smaller-sized electronic equipment. Thus, an approach has been carried out, which involves mounting on a lead frame an integrated circuit chip having various LSI (large scale integrated) circuits, and encapsulating with resin the integrated circuit chip mounted on the lead frame.
The description is given with regard to a conventional semiconductor device with reference to FIGS. 8 to 10.
FIG. 8 is a plan view of a conventional lead frame having an integrated circuit chip mounted thereon. FIG. 9 is a perspective view of a semiconductor device using the lead frame. FIG. 10 is a perspective view of the semiconductor device using the lead frame as mounted on a conductive pattern.
As shown in FIG. 8, a lead frame 1 includes an island 3 on which an integrated circuit chip 2 is mounted, and a plurality of leads 4A, 4B, 4C, . . . , and 5A, 5B, 5C, . . . , which act as external electrode terminals. The leads 4A and the like are arranged in DIP (dual in-line package) form and spaced at predetermined intervals.
The integrated circuit chip 2 is mounted on the island 3 of the lead frame 1. Electrodes 6A, 6B, 6C, . . . , and 7A, 7B, 7C, . . . placed on the integrated circuit chip 2 are respectively bonded to the leads 4A and the like through fine metal wires 8A, 8B, 8C, . . . , and 9A, 9B, 9C, . . .
As shown in FIG. 9, a resin-sealing body 10 is formed so that the outer portions of the leads 4A and the like are exposed to the outside thereof, and thus a semiconductor device 11 is completed.
As shown in FIG. 10, in the semiconductor device 11, the ends of the leads 4A and the like are brazed (e.g., soldered or otherwise bonded) to conductive patterns 14A, 14B, 14C, and the like on a printed wiring board 12.
As mentioned above, the semiconductor device includes the integrated circuit chip, which is increasing in size year by year. Thus, the heat generated by the integrated circuit chip and the like can cause thermal damage to the integrated circuit chip or the semiconductor device. Although it is therefore necessary to improve heat dissipation characteristics of the semiconductor device, the semiconductor device has the problem of inadequate heat dissipation because the integrated circuit chip and the island having the chip mounted thereon are integrally molded with resin. Moreover, the lead frame having a larger number of pins becomes thinner and thus there was the problem of impairing the heat dissipation characteristics.